HomeMy WebLinkAboutTechnical Memorandum
1
TECHNICAL MEMORANDUM
TO: Ray Griswold/Deputy Fire Marshal/NHC Fire Rescue
FROM: Drew Hatcher, PE
DATE: February 11th, 2025
RE: 84 Lumber – Wilmington, NC
Water Hydraulic Modeling
M&C#: 03272-0006
I. Introduction and Background
The purpose of this Technical Memorandum (TM) is to evaluate water demands, fire flow
demands, and system pressures for the 84 Lumber industrial site, a proposed storage area, located
in New Hanover County. The demands are based on design drawings provided by the design
engineer and the system evaluation will be based on results obtained through hydraulic modeling
in WaterCAD software. The proposed development is located on approximately 9.37 acres in
New Hanover County. 84 Lumber is expected to include a 50,000 SF (+/-) Storage Building with
loading docks and employee parking and will be connecting to an existing 8” water main stub off
of Hall Drive (SR 1386).
II. Water Demand Projections
The water demand projections are based on a NCDEQ flow factor of 25 Gallons Per Shift, Per
Employee. 400 GPD has been allotted for the storage facility. The storage building is 50,000 SF,
Type IIB and sprinklered, requiring a minimum of 1,200 GPM at 20 PSI based on the 2024 NCFC,
Table 507.3(1) and Table 507.3(2).
III. Modeling Assumptions
Information provided by the designer was incorporated into the master model, including pipe
design, material and alignment, layout of proposed structures, and ground elevations. The
following hydraulic modeling assumptions were made:
· Hazen-Williams C = 130
· Maintain 1,000 GPM fire flow at a minimum 20 PSI residual pressure at all
proposed fire hydrants.
· Maintain 1,200 GPM fire flow at a minimum 20 PSI residual pressure at the fire
service node serving the sprinkler system within the Storage Building.
2
IV. Modeling Results
A schematic representation of the 84 Lumber development can be seen in the calculation
attachments herein. Based on the hydraulic modeling results presented in Appendix A, the
minimum calculated pressure meets the required minimum pressure of 20 PSIG:
Minimum calculated pressure at peak demand (ADF + fire flow) =
42 PSI where 1,000 GPM Required
41 PSI where 1,200 GPM Required
V. Summary
Based on the information provided by the designer and the hydraulic modeling results presented
in this Technical Memorandum, the water mains for the 84 Lumber project are adequately sized to
maintain the minimum 20 PSI residual pressure at peak demand (domestic plus fire flow) to the
proposed community. A summary of the anticipated project flows is as follows:
Provide anticipated project flows for any project that will increase demands:
Does the proposed project include any in-ground irrigation?
O Yes X No
If yes, attach appropriate analysis to address how the system is
designed to accommodate the impact of irrigation use on treated
water supply, storage needs and system pressure.
Peak demand of the proposed project
Maximum daily demand of the proposed project
0.70 gpm
1,000 gpd
Per Rule .0901, are the water mains and water system designed to
carry fire protection flows for this project?
x Yes □ No
If the water mains and water system are designed to provide fire
protection flow, indicate the minimum calculated pressure at peak
demand (domestic plus fire flow). Pressure must be at least 20 psig
per Rule .0901.
41 psig